Current Evidence for Dietary Therapies in IBS

Abstract and Introduction

Abstract

Purpose of Review: Diet appears to trigger symptoms in the majority of individuals with irritable bowel syndrome (IBS) and is associated with a reduced quality of life. There has been a recent focus on the role of dietary therapies to manage individuals with IBS. The aim of this review is to discuss the utility of traditional dietary advice (TDA), low-FODMAP diet (LFD) and gluten-free diet (GFD) in IBS.

Recent Findings: Several recent randomized controlled trials (RCTs) have been published demonstrating the efficacy of the LFD and GFD in IBS, with the evidence base for TDA being predominantly based on clinical experience, with emerging RCTs evaluating TDA. Only one RCT has been published to date comparing TDA, LFD and GFD head to head, with no difference noted between diets in terms of efficacy. However, TDA has been noted to be more patient-friendly and is commonly implemented as a first-line dietary therapy.

Summary: Dietary therapies have been demonstrated to improve symptoms in patients with IBS. In view of insufficient evidence to recommend one diet over another currently, specialist dietetic input in conjunction with patient preference is required to determine implementation of dietary therapies. Novel methods of dietetic delivery are required in view of the lack of dietetic provision to deliver these therapies.

Introduction

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction (DGBI), characterized by chronic abdominal pain and alteration in bowel habit.^[1] It is common, with a reported prevalence of 4.1%, using the Rome IV criteria for diagnosis.^[2] The impact on quality of life is significant, impacting on psychological comorbidity and healthcare utilization, with worsening outcomes in individuals affected in multiple gastrointestinal areas of DGBI.^[3] Options currently available for management include pharmacotherapy, dietary therapy and psychotherapy, with the most preferred treatment option for patients being dietary therapies.^[4]

The majority of individuals with IBS note symptoms to be triggered by food, reported as high as 84%, with self-reported food intolerance being associated with a high symptom burden and reduced quality of life.^[5] Recent literature had focussed on the role of traditional dietary advice (TDA), the low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) diet and gluten-free diet (GFD). The aim of this review is to provide an update on the current evidence for implementation of these dietary therapies in IBS.

Table 1. Key studies evaluating comparative efficacy of dietary therapies
Lead author	Total number of participants	Comparator diets	Outcome
Bohn [10]	n = 75	TDA and LFD	Severity of IBS symptoms improved following both interventions, with no difference between groups (P = 0.62)
Eswaran [15]	n = 92	mNICE and LFD	No difference in adequate relief of symptoms between both groups (P = 0.31)
Zahedi [12]	n = 110	TDA and LFD	LFD significantly improved overall gastrointestinal symptom scores (P < 0.01), stool frequency (P < 0.01) and consistency (P = 0.003) compared with TDA
Paduano [53]	n = 42	LFD, GFD and Mediterranean diet	No difference in reducing disease severity between all three groups (P < 0.01)
Goyal [13]	n = 101	TDA and LFD	Responders to LFD significantly higher than TDA group at week 4 (P = 0.0448) and week 16 (P = 0.0274)
Rej [11]	n = 101	TDA, LFD and GFD	Similar improvement in symptoms between all three groups (P = 0.43)

Adapted from Rej et al. [93]. GFD, gluten-free diet; mNICE, National Institute for Health and Care Excellence; LFD, low-FODMAP diet; TDA, traditional dietary advice.